Rental car - rent from Dublin airport or downtown Dublin?

Forget option 1 unless you know your way around Dublin and know where to park. I would vote for option 2, consider someplace like Malahide or Trim - although you would still have to drive the M 50 to get to Kilkenny. Re option 3, many of the rental agencies allow you to rent from the airport and return to the city center or vice versa without a one way drop fee.

The airport. Easy to do.

Rent car at the Airport...do not try driving in Dublin City unless you’ve done it before...successfully.
My wife and I recently were in Ireland for a RS Tour...absolutely loved it and had a great time.
After the Tour we rented a car at the Airport and drove to Kilkenny on our own...avoiding Dublin...with no issues.
Get a taxi to take you in and out of Dublin.
The Rick Steves office had given us great advise before the Tour...very glad they did...including the rental car process.
Enjoy Ireland!

Airport tends to have a greater supply of cars, but a bigger advantage is the location as it's easy to reach just about all of the national road network without having to go back into the city.

You'll have a better chance of getting an automatic if you collect your car at the airport, since they generally have a larger selection of vehicles.
I agree - don't drive in central Dublin, especially if this will be your first adventure driving on the left.
The airport car rental offices open early, ie around 5 AM in most cases whereas the satellite lots in the city usually don't open until 8:30 or so, so if getting on the road early is a consideration then the airport is the way to go.
Be aware that the actual rental car lot is located on Swords Road - about a mile from airport. Taking a taxi from your accommodation directly to the rental car lot on morning #2 will save you both time and aggravation.

Get the car at the airport, many choices of vehicle types and sizes and no major traffic problems early on. We took the bus into Dublin and then took a taxi bck to the airport as we were departing for the US. For me, the extra money for the taxi was well spent and if I had it to do over again I would take the taxi both ways, it was like 30 bucks for two of us...I would get the car at the airport and drive to Kilkenny on Thursday, its like a two hour drive and you will be on the "bypass" not in downtown Dublin. You'll be struggling with jet lag but I'd give it try. One thing I did was look at the route on Google Earth street view to familiarize myself with the route. It was helpful (we were going west Cong) but one thing that was somewhat confusing was the location of the car pickup at the airport was not where street view showed the Hertz location. We had to adjust when trying to find our way to the M50 so make sure you get some directions from the desk for the car pickup location to the M50. Then return the car to the airport and either stay out there or take a taxi in to Dublin if your plans are to visit in Dublin any amount of time. On our return we had an early early flight but had no problem with a taxi picking us up at our Temple Bar area B&B at 5 AM for return to the airport.

Thank you all - this forum never disappoints. I appreciate the recommendations, and think we will get a car at the airport and drive to Kilkenny directly.

Our busy experience- I must qualify by saying that for this trip, we tried to pack in as much as possible in a short time. we usually don't- but I can still advise this plan from Dublin to Kilkenny. 2 and a half days.These are my notes from Ireland 2018. I'm a complete researcher and like to plan my own trips.
We are going on a Rick Steves tour to Italy with friends in Sept. 2020. First guided trip.

We spent three weeks in Ireland but this is our plan for first days to Kilkenny...It is jam packed action..but "doable" if you are trying to see some things. Not highly recommended if you like to take your time and relax, but just giving you some fun options if you don't mind being busy. By the way, later in our trip we definitely slowed down! Highly recommended to slow down later. (All- Please dont give me any "shade" for the hurried pace- trying to compromise with dear hubby...)
We rented a car at the airport the next day after arriving in Dublin. (Dooleys car rental- you must get the insurance- not covered by most US insurance agencies.. check your carrier- ) We spent the night in Dublin at Buswells hotel, decent and centrally located..., (DUBLIN tours- Book of Kells early admission from Viator - and also Jameson Cocktail making class, and Kilmainham Jail tour- Guiness walk thru- Brazen Head stop...besides walking thru cathedrals and taking pictures, looking and enjoying) We also went to St. Michans by accident and some strange lovely fellow took us down into the catacombs (ancient bones buried in the basement) very cool and unexpected treasure. We had so much fun with people at the pubs and just walking around. Next morning took a taxi back to the airport car rentals (we used Dooley and they were great)) and incorporated driving to Glendalough the next day ourselves with a private tour at our destination point.
I highly recommend Glendalough location if you have the time. It is magical especially if you have a private guide. Beauty abounds! Look at Rick Steves recommended drive if you are driving yourself to get there. We met some stampeding sheep and had the most beautiful views! Plus... the sun came out!! Next- the tour of Glendalough- privately booked-We were lucky to have Martin Swords and he was great. Then-after the tour..We drove to Kilkenny that afternoon. Highly recommend Kilkenny- atmospheric lovely town. We stayed in Kilkenny Castle hotel. Great location- get a castle view room- don't get room above the kitchen...(greasy smoke all night, still amazing views but ASK for something different- no worries really but if I had the chance to ask for something differnet I would)
Booked Kilkenny Sunset cycling tour that same evening...(August travel) we LOVED it! So much fun! met local people (priest) and had the best time! Kilkenny is a great stop. I advise going to pubs in the evening- we loved the original music at Kytelers Inn. The music was magical!! We visited the castle in the morning before leaving the next day. Headed to THE ROCK OF CASHEL. Next!
Hope this gives you some good guidance- Happy travels! Lisa

Not sure if I highlighted it- but dont get a car in Dublin_ get it when you leave Dublin- head back to the airport, pick up a car and continue on your journey. Happy travels!

We were on a RS tour last October, and when the tour ended we took a taxi to the airport. I thought we should be dropped at the rental return place on Swords Rd, but the taxi dropped us right at the terminal, and we were able to pick our car up right there. Very easy.

When we got back a week later, I had booked a hotel right at the airport. Maldron Hotel. We dropped the car on Swords Rd. rental return, took the shuttle back to the airport, and had a 10 min walk to our hotel. The next day the shuttle took us with all our luggage to the airport.

So glad I didn’t have to drive in Dublin. It was very easy driving on the highways around the city.

Excellent posts - thank you for the information!!